132 ROSACEAE. 



Leaves pinnate; recep- 

 tacle not fleshy. 

 Flowers dark purple; 



receptacle spongy. 202. Comarum, 141. 

 Flowers yellow or 

 whitish ; recep- 

 tacle dry. 

 Plant stolonifer- 

 o u s ; flowers 



solitary. 203. Argentina, 142. 



Plant not stolonif- 

 erous ; flowers 

 cyraose. 204. Drymocallis, 142. 



184. PRXJNUS. Plum. Cherry. 



Small trees or shrubs, many with edible fruits ; leaves alternate, 

 simple, usually serrulate; flowers white or rose-colored, solitary 

 or fascicled in the axils or in terminal racemes or corymbs ; calyx 

 5-lobed, free from the ovary; petals 5, on the receptacle-cup; 

 stamens numerous; pistil 1; style 1; ovary 1-celled, 2-ovuled; 

 fruit a drupe; seed 1, rarely 2; endosperm none. 



Flowers racemose. P. demissa. 



Flowers corymbose. P. emarginata. 



Prunus demissa (Nutt.) Dietr. Chokecherry. Shrub or small tree, 2-8 m. 

 high; leaves ovate or oblong-ovate, cuneate, rounded or cordate at the base, 

 sharply serrate, 5-10 cm. long, sometimes somewhat pubescent beneath; 

 petioles 1-2 cm. long, appearing after the leaves; calyx somewhat glandular; 

 petals nearly orbicular; fruit globose, dark purple, 5-6 mm. in diameter, not 

 edible; stone globose. Common along streams. 



Prunus emarginata (Dougl.) Walp. Wild Cherry. Shrub or small tree 

 3-8 m. high; branches and bark chestnut brown, with prominent lenticels; 

 leaves narrow, ovate, elliptical or obovate, obtuse or acute, cuneate at base, 

 minutely serrate, glabrous or pubescent beneath, 3-8 cm. long, short-petioled ; 

 corymbs few-flowered, appearing with the leaves; flowers about 1 cm. broad; 

 fruit oblong, bright red, bitter; stone with a grooved ridge on one side. In 

 dry open places in the mountains. 



185. CERCOCARPUS. 



Shrubs or small trees with alternate simple petioled leaves; 

 flowers perfect, solitary or clustered, axillary or terminal, sessile 

 or nearly so; calyx narrowly tubular, 5-lobed; petals none; 

 stamens 15-25, perigynous; pistil 1, narrow, terete; fruit a 

 coriaceous, linear, terete akene with a long exserted plumose 

 twisted style. 



Cercocarpus ledifolius Nutt. Mountain Mahogany. Scraggly shrub or 

 tree, 3-10 m. high; leaves coriaceous, lanceolate, entire, acute, 1-nerved, 

 tomentose beneath, usually glabrous above, short-petioled, 2-3 cm. long, the 

 margins more or less inrolled; flowers sessile, tomentose; tail of the akene when 

 mature 5-7 cm. long. In sheltered places on high ridges in the Blue Moun- 

 tains. 



